The purpose of the investigation is to clarify the mechanism by which fat and bile in the intestine influence gastric secretion. Specific experiments which will be carried out: 1. in dogs with Heidenhain pouches gastric secretion will be stimulated by irrigation of antral pouches with acetyl choline; the effect of instillation of fat into the proximal gut on serum gastrin and Heidenhain pouch secretion will be documented before and after small bowel resection. 2. The effect of bile and fat, instilled into the duodenum individually and in combination, on Heidenhain pouch secretion will be ascertained. 3. Irrigation of Thiry-Vella loops of jejunum and ileum with whole bile and bile salts will be carried out and the affect of such irrigations on Heidenhain pouch secretion will be studied.